Ignition system



Feb. 8, 1949. BROWN 2,461,196

IGNITION SYSTEM Filed Feb. 25, 1948 IN VEN TOR.

W {M JAM/M 6734 Patented Feb. 8, 1949 IGNITION SYSTElVI William E. Brown, Anderson, Ind, assignor to General Motors Corporation, Detroit, Mich a corporation of Delaware Appiication February 25, 1948, Serial No. 10,657

1 Claim. 1

This invention relates to ignition apparatus for automotive vehicles and its aim is to circumvent theft of an automobile by one who uses a jumper which can be quickly connected to the coil and battery terminals of the ignition switch, thereby maintaining ignition operative although the switch may be locked in Off position. This object is accomplished by a specially constructed ignition switch whereby the ignition coil terminal of the switch will be connected with the battery terminal when the movable contact of the switch is in On position and will be connected, when the movable contact is in Off position, through a resistance to means connecting the ignition coil with the ignition timer contacts and the condenser which parallels the contacts.

Further objects and advantages of the present invention will be apparent from the following dmcription, reference being had to the accompanying drawing, wherein a preferred embodiment of the present invention is clearly shown.

In the drawing the single figure is a wiring diagram of the present invention.

The switch ID has a movable contact of triangular formation which when in the On position represented by the triangle I! in dot-dash lines connects a terminal l2 directly with the storage battery B with a terminal is connected with the primar winding 20 of an ignition coil C and also with a terminal I 4 for making connection with an instrument (not shown). When the movable switch contact II is in Off position, as represented by the dash line triangle 5 I, an extension l3a of the terminal I3 is connected with a terminal l5, which is connected through a resistance It with that end of the primary winding 20 which is directly connected with the ignition timer T. The timer T includes a contact 2| engaged by movable contact 22 carried by lever 23 pivoted at 24 and urged clockwise by a leaf spring 25 connected with the lever and with a terminal 26. The engagement of a cam 21 with a, rubbing block 28 on the lever causes the contacts to separate when an ignition spark is required. A condenser 29 is connected with the terminal 26 and parallels the timer contacts. The secondary winding 30 of the ignition coil C is connected with the rotor 3| of the distributor D having terminals 32 to which sparking impulses are distributed by the rotor 3| so that sparking will occur at spark plugs 33 in recurrent sequence.

When the switch I0 is Off, the movable contact is in the position of H, and th battery B is disconnected from the coil C and the engine cannot be started, although it may be cranked by a starting motor. If a thief, in an attempt to steal the car, bridges across the terminals [2 and [3 by a jumper 40, the ignition coil primary 20 will receive very little current from the battery B since both ends of the winding 20 are practically at the same potential, the only difference being the voltage drop across the resistance It which prevents a direct short circuit of the battery in case the ignition timer contacts are closed. Furthermore the condenser 29 is so connected that it cannot discharge through the ignition coil even though it had had a charge which might cause ignition. When the switch is closed, the discharge circuit for the condenser is through the resistance l6, terminal 15, terminal 13, jumper 40, terminal l2 and battery B to ground rather than through the inductive primary winding 20. lgnition is not possible because primar 20 is practically short-circuited and the condenser 29 would not discharge through the primary 20.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claim which follows.

What is claimed is as follows:

An ignition system comprising a current source, an ignition coil having a primary coil and a secondary coil, a timer having a contact connected with one end of the primary coil and a contact connected with the source and engaged by the first mentioned contact, a condenser having a terminal connected with the first contact and a terminal connected with the source, a switch having a first terminal connected with the source, a second terminal connected with the other end of the primary coil and having a third terminal, a resistance connecting th third terminal with the. primary coil end first mentioned, a movable contact of the switch which, when in On position, connects the first and second terminals and which, when in Off position, connects the sec. 0nd and third terminals, whereby the primary coil ends are shunted through the resistance and connection of the first and second terminals while the switch is On will provide a path of condenser discharge through the resistance and bypassing th primary coil.

WILLIAM E. BROWN. No references cited. 

